Sling-it the molds used to make these samples are VERY rare. Having worked in several old mills that once ran open hearth furnaces, these molds were scrapped decades ago or are lost to the dust and dirt. I would reach out to US Steel and ask if they have archive drawings you can browse for a "Sample Mold". Several of the mills I worked at had the drawings for the molds they used and you could take that to a local foundry to be reproduced. As far as the process, one of the "Helpers" would pull a sample of molten steel using a long spoon and another helper would deoxidize or "kill" the sample in the spoon with some aluminum wire. The helper would then pour the steel into the mold and let it solidify. These samples varied from mill to mill but most were approximately 1.5" square and 6 inches long. Once solidified, they would knock the sample out and quench it. This is where your anvil comes in....the cooled sample would be set on the step of the anvil and a sledgehammer would be used to break the sample and expose the grains. This visual check would be used by the melters to determine the carbon and silicon in the steel during the process. Many melters could determine the carbon content of the heat to within a few hundreths of a percentage point based on the grain sizes.
